Process of recovering potassium chlorid from saline waters.



omen STATES PATENT OFFICE,

GEORGES. vHU RNI'IAIII OF BERKELEY, CALIFORNIA.

PROCESS OF RECOVERING POTASSIUM CHLOBID FROM SALINE WATERS.

No Drawing.

Tour/.75 a r/(0m [1 may (VI/U387? lie it known tlmtl. Grown-z l). lu'uximu, a. citizen of the lnited States. and a resident of Berkeley, county oi Alameda. and State of (alii'ornizn have invented a certain new and useful Process f Recovering Potassium Cl lorid from Saline \Yaters, of which the following is a specification.

The invention relates to a process of recovering potassium chlorid t'rom saline waters and particularly from the brines ot' the alkaline lakes ofthe western l nit'ed States.

An object of the invention is to provide a cheap process for recovering potassiun'i chlorid from saline waters containing the same.

The invention possesses other advantageous i'eatures some of which. with the foregoing, will be set forth at length in the fol: lowing description where I shall outline in full one form of the process of my invention. I shall describe the process as applied to'thc brine ot Searle. Lake in ('alifornia. but it is to be-umlersttmd that the process is not limited to this particular brine.

t'iearles Lake brine contains sodium, and potassium, chlorid. sulfate. carbonate and borate, and is nearly saturated with sodium ehlorid. When a brine is encountered which is not saturated with sodium chlorid, it is necessary to bring it to saturation with so dium chlorid and to maintain it at saturation or nearly so throughout the process. By the process of my invention I am able to employ natural temperatures tor evuptlltttlml and cooling without causing the torn'iation of double salts of potassiun'i, so that single salts only are separated from the liquor. I prefer to make use of the temperature variations of winter and summer. but in some lllStflllCP it may be possible to carry out the process with the (litter-ac... in temperature between day and night and also artiiicial variations in temperature may be employed.

In the preferred form of the process, the brine is pumped -t'roni the lake in December into a large shallow vat which is partitioned oil into a series of smaller vat The brine is pumped continuously througl'iout the month and in twenty-four hours the first small 'at. is tilled, and at daybreak, when the brine is at its coldest. it is allowed to flow into the second at of the series. At daybreak the next day, the second small vat is emptied into the third vat and the first, into he second vatand so on, and this process is tontinued day after day until all of the Specification of Letters Patent.

Application filed December-20. 1917.

Patented Dec. 10, 1918.

Serial No. 208,081.

carbonate in the second half of the series. all.

due to the chilling of the brine to lower and lowertemperatures in the succeeding shallow vats. sodium chlorid, this will be crystallized out by evaporation throughout-the series. but, this can be prevented if desired by adding suliicient water to the brine-to compensate Since the brine is saturated with s for the water of crystallization that; is taken up by the crystals deposited, and the evaporation.

The object of the series of shallow vats is to cause a low temperature to be reached (approximating -4 C. at Searles Lake) and also to minimize the heat of crystallization by depositing only a portion of the crystals in each vat. Crystals will re-dissolvc in solution much slower than they will crystallize out and hence the series of vats prcvents re-solution of the crystals during the warmer temperature of the day.

When the brine has passed through the series of shallow. vats, wherein sodium sulfate, sodium borate; sodium carbonate and sodium chlorid, have been crystallized 0ut,itis flowed J into a la rge winter evaporating vat, the depth of which should be such that approximately llf/rv of the water will be evaporated in this and the prior vats before the end of the cold season. A small amount of sodium salts will be deposited in this vat, but on account of the low temperature and saturation of the brine with sodium chlorld, no double.

salts of potassium are formed. From the large vat the brine is flowed during February into a series of shallow vats. in order to obtain the greatest chillihgeifect possible and to prevent supersaturation by keeping the brine in motion.

From the shallow vats the brine is flowed into the main summer evaporating vat which should be about six feet deep in order to secure the desired evaporation and to insure an approximately et'en temperature between day and night. Sodium chlorid will be crystallized out in this vat and the brine becomes nearly saturated with potassium chlorid and is nearly saturated with a double potassium salt, and (-are must he taken that the evaporation is not. continued lone enough to produee crystallization of this double saltand still at the same time keep the brine at as high temperature as possible to the, point of saturation with Ktl.

During July and August the brine is flowed into a shallow \at so that it may reach a high r temperature. the vaporization in this and the prior vat equalingaliout 38)? of the brine. The depth ot the lnine in the shallow \Ht is such that it will heroine saturated with l :(l at the highest teinperature reached during the middle of the day. \Vhen this condition of saturation'is reached the brine is flowed into a deep vat to minimize 't'urther e \':q)oration. in which the brine cools until winter, thereby erystallizing out. K(l. Since the lHlllt is saturated with sodium elilorid.the small amount of evaporation which occurs in the deep vat will tend to cause sodium ehloritl tolie crystallized out, hut this may lie i'n'evented by adding: sutlieient. water to the brine in the rat to (.Ull'lpensate for the losshy tw'aporation. therehy insuring a purer quality of l (l. The urine is allowed to cool in the deep vat until it almost rearhes saturation with sodiuin'earlionate or sodium sulfate. that is, about 5 at which temperature about one-third of the K(,l is crystallized out. Agtuither re duction of temperature would produce an undesired deposit of sodium carbonate and sodium sulfate. The. remaining liquor is then flowed hack to the first. vat and mixed with fresh brinetromthe lake and the process is repeated. The addition of this residual liquor inereases the percentage of potassium in the brine to such an extent that after passing through the series of shallow vats, the brine may he flowed directly into the main summer evaporating vat. If the coneentration of KCl in the hrinecaused by mixing the mother liquor with the lake brine) is greater than the ln'ine can hold at its cool- ,ine stage then water must he added to the rat in winter to preyent Kill from crystallizin'g out on cooling. In the first year of the process. it is necessary to evaporate water during the winter, but in the second year and each year thereafter. as long as the lake lirinejcontinues its present; composition, it. is necessary to add water in winter in ordertosupply water of crystallization for the sulfates. carbonates and horates, and

thereby 'prevent. the crystallization of potas sium chlorid in the first evaporating rats.- 1 claim: a 1.'-;The process of recovering potassium chlorid' fronrliquors containing potassium, and sodium. ehlorid, sulfate and carbonate, and approximately saturated with sodium chlorid, which consists in cooling the liquor "carbonate,

to crystallizeout sodium sulfate and sodium removing the llquortrom the (18"- I posited crystals, raisiru. the temper:

lure of the liquor and evaporating a p tion of the water, whereby sodium chlorid is erys allized out and the liquor is appt'oximately saturated with potassium rhlorid. separating! the warm liquor from the deposited (.i' ,'t-'l't\l and cooling the liquor to erystallize out potassium ehlorid.

,The process of recovering pota sium chlorid from liquors containing odium, and potassium, elilorid, sulfate and rar au ate and approximately saturated with .--o inuu ehlorid. which consists in chilling" and partially evaporating the liquor whereby odium sulfate, sodium earlionate and -Utllllltl chlorid are crystallized out. separating the ehilled liquor from the deposited erystals, heating the liqu and evaporating a portion of the water, \\"herel y sodium ehlorid is rrystallized out and the -arm liquor he comes saturated with potassium rhlorid, separating the warm liquor i'rom the deposited crystals, cooling: the liquor whereby potassium ehlorid is rrystallized out, and adding water to the liquor to prevent crysitllllZtlllOILOf the sodium chlorid.

3. The process of recovering potassium chlorid t'rom liquors containing sodium, and potassium, chlorid, sulfate and carbonate, which consists iircoolirig the liquor, whereby sodium sulfate and sodium carbonate are crystallized out, bringing the liquor to seturation with sodium ehlo'rid by evaporation, separating the liquor from the deposited crystals, heating the liquor to e 'aporate a portion of the water and crystallize out sodium' ehlorid and bring, the liquor to approximate saturation with potassium chloral, separating the warm liquor from the deposited .erys tals and chilling the liquor to crystalcrystals,'heating and evaporating the liquor to crystallize out sodium chlorid and bring the liquor to near saturation with potassium chlorid, separating the Warm liquor from the de )osited crystals, coolingthe liquor to crystal ize out potassium chlorid, separatingthe liquor from the deposited salts and adding it to a fresh supplyoftho'original liquor and repeating the steps of the process.

5. The process of recovering potassium chlorid from liquors containing potassium,

and sodium, chlorid, sulfate and earbonate which-consists in cooling the liquor toorys tallize ut sodium sulfateand sodium-earbonate and bringing the solutioii to up roilimate Saturation with sodium chlori,

the original arating the cool liquor from the deposited crystals, heating and evaporating the liquor to crystallize out sodium chlorid and bringing the liquor to near saturation with potassium chlorid. separating the Warm liquor from the deposited crystals, cooling the liquor to crystallize out potassium chlorid, separating the liquor from thedeposited salts, adding the liquor to a fresh supply of liquor, adding water to the liquor. and continuing the process.

6; The process of recovering potassium chlorid from liquors containing sodium, and potassium. chlorid, sulfate and carbonate. and approximately saturated vith sodium chlorid, which consists in flowing the liquor in Winter in hallow vats wherein it is chilled and partially evaporated whereby sothe water contents suflicieintly to crystallize out sodium chlorid and approximately sat-urate the liquor with potassium chlorid, flowingthe warm liquor into a deep vat at t e end of summer and allowing it to 0001 in the deep vat, whereby potassium chlorid is crystallized out, and preventing the crystallization of sodium chlorid in the last deep 'vat. In testimony whereof, I have hereunto set my hand at San Francisco, California, this 11th day of December, 1917.

.GEORGE B. BURNHAM. In presence of- H. G. Pnosr. 

